Oil Spill Dispersants Efficacy and Effects (2005) / Chapter Skim
Currently Skimming:
2 Making Decisions About Dispersant Use
2 Making Decisions About Dispersant Use
Pages 21-50
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 21... ...
Structurally, the national response system is comprised of three organizational levels: National Response Team (NRT, co-chaired by the U.S. Coast Guard and the Environmental Protection Agency)
|
From page 22... ...
At the time of an oil spill incident, a FOSC may authorize the use of dispersants on oil discharges upon concurrence of the federal co-chairs and the state representative to the RRT and in consultation with the federal natural resource trustee agencies, the U.S. Department of Commerce (DOC)
|
From page 23... ...
Coast Guard and EPA co-chairs, as well as state and federal trustee agencies)
|
From page 24... ...
Coast Guard recently proposed mandatory capabilities to apply dispersants (where preauthorized) within 12 hours of the initial discovery of the release.
|
From page 25... ...
All response options, based on the rapidness of deployment and oil fate regimes, have consequences inherent in their selection. Decisionmakers are forced, by the very nature of response to oil spills in the marine environment, to identify environmental and economic trade-off choices in real time, adequately assess the risk associated with each choice, Ecological risk assessment Political issues Social factors Ecological risk management decision Costs/Benefits Technological feasibility Regulatory and legal requirements FIGURE 2-2 Relationship of ecological risk assessment to management decisions SOURCE: Modified from Pittenger et al., 1998; courtesy of Alliance Communications Group.
|
From page 26... ...
Obtain concurrence from the NO incident-specific EPA representative Consult with DOC and to the RRT and the RRT state DOI Natural Resource representatives with jurisdiction Trustees NO Mechanical response Concurrence techniques used obtained? Response action Consultation YES Initiate use of chemical countermeasure FIGURE 2-3 Example decision flow chart for using chemical countermeasures or dispersants showing federal and local responsibilities in the United States.
|
From page 27... ...
Once the potential for damage caused by a particular oil spill has been established, the potential reduction in the amount of damage achievable by each of the response options (e.g., mechanical recovery, dispersants, in-situ burning, or do nothing) can be assessed.
|
From page 28... ...
Continuous D.5 reassessment Will use reduce overall No impact? Focus on Apply mechanical dispersant response FIGURE 2-4 Idealized decision flow chart for evaluating the appropriateness of using chemical dispersants as a response option in the United States.
|
From page 29... ...
properties that play a significant role in determining whether a specific dispersant will effectively disperse a surface slick under ideal conditions. Early in a spill response, decisionmakers should rapidly determine the nature of the fresh oil or product, how it will change over time, how effectively available dispersants are known to treat a specific oil or product under ideal circumstances, and how far from ideal circumstances does the particular spill deviate.
|
From page 30... ...
The type of dispersant application platform used directly controls the operating distance offshore and amount of dispersant that can be applied in a day. Table 2-1 presents a summary of the capabilities, advantages, and disadvantages of different platforms that might be used to apply dispersants in the United States.
|
From page 31... ...
Good speed (90 kt) Limited range Equipment easily adaptable High maneuverability High accuracy Vessels 10 2 2,000 30 1 1,000 Advantages for vessels: Disadvantages for vessels: Readily available Slow speed Easily adapted Low daily application rate High payload Maneuverability aThe number of sorties per day and thus the amount of dispersants sprayed per day is a function of the operating distance.
|
From page 32... ...
is whether sea state condition and weather allow for dispersant use. Waves provide most of the mixing energy needed to break surface oil into droplets and mix them into the water column.
|
From page 33... ...
For small spills, mixing energy can be added by driving boats through the treated slick or applying water spray, such as from a fire hose or spray system, after the dispersant has been successfully applied to the slick. Evaluating Possible Ecological Consequences To adequately evaluate the use of dispersants on marine oil spills, environmental managers and decisionmakers need to assess the ecological risk and consequences associated with any given decision.
|
From page 34... ...
In the case of oil spill planning, the goal is different from ecological risk assessments of proposed projects since the spilled oil cannot be prevented from entering the environment -- the goal is to minimize adverse effects. Environmental planners and decisionmakers should evaluate scenarios for the expected range of incidents and focus on providing information tailored to meet the circumstances of a particular spill.
|
From page 35... ...
Ecological Risk Assessment Applications for Oil Spill Response in the United States This section summarizes a process of a cooperative ecological risk assessment (ERA1) currently utilized in many regions of the United States to evaluate the ecological trade-offs associated with the use of each of five potential oil spill response options: natural recovery, on-water mechanical cleanup, shoreline cleanup, dispersant use, and on-water in-situ burning.
|
From page 36... ...
Prepare Supplemental Technical Papers Characterize Potential Effects Characterize Potential Exposure PHASE 3: Risk Characterization Meeting 3 Final Report * Small Workgroup and *
|
From page 37... ...
. Although the primary stressor may be the oil itself, unique environmental stressors result from human intervention through on-water mechanical recovery, shoreline cleanup, dispersant application, in-situ burning, or any other response options.
|
From page 38... ...
Shoreline Deep Water Coastal Water Colu Cleanup Aqueous (>35 ft) SPILL Exposure Kelp Forest Eelgrass/Algae Shallow Softbottom (<35 ft)
|
From page 39... ...
spill scenario. Throughout the ERA process, any adverse impacts resulting from a response option are always compared against natural recovery.
|
From page 40... ...
TABLE 2-3 Workshop Consensus on Exposure Concentration Thresholds of Concern for Dispersed Oil in the Water Column in the Texas Ecological Risk Assessment (ERA) Level of Level of Sensitive Adult Adult Crustacean/ Exposure Concern Life Stages Fish Invertebrates 03 hours Low 1 10 5 Medium-low 15 1050 510 Medium-low 510 50100 1050 High 10 100 50 24 hours Low 0.5 0.5 0.5 High 5 10 5 96 hours High 0.5 0.5 0.5 NOTE: All numbers are in parts per million (ppm)
|
From page 41... ...
Trivial FIGURE 2-9 Basic ecological risk matrix design. SOURCE: Kraly et al., 2001; courtesy of the American Petroleum Institute.
|
From page 42... ...
In Phase 3, the participants begin to examine the matrix vertically, comparing relative impacts of each stressor on a given segment of the environment, allowing determination of which response option or combination of options should provide optimum protection of the environment as a whole. The first step in risk characterization revisits the risk square to determine whether individual scores represent a high, medium, or low threat to the environment.
|
From page 43... ...
Note: clear cells represent a "minimal" level of concern; light gray cells represent a "moderate" level of concern; and dark gray cells represent a "high" level of concern. SOURCE: Kraly et al., 2001; courtesy of the American Petroleum Institute.
|
From page 44... ...
SOURCE: Modified from Kraly et al., 2001; courtesy of the American Petroleum Institute.
|
From page 45... ...
However, the awareness and understanding that a specific group of decisionmakers share by participating in a risk assessment process greatly facilitate real-time decisionmaking. IDENTIFYING INFORMATION NEEDED TO SUPPORT EFFECTIVE DECISIONMAKING As depicted in Figure 2-4, the availability of different pieces of information (about the environment, spilled oil or refined product, and response assets available)
|
From page 46... ...
Although mechanical response techniques have the advantage of removing spilled oil from the environment, their ability to do so is somewhat limited. Under ideal conditions, some portion of the spill cannot be recovered and under adverse environmental conditions (e.g., high sea state)
|
From page 47... ...
Coast Guard rulemaking would establish mandatory capabilities to apply dispersants in preauthorized zones within 12 hours of the initial discovery of the discharge within 50 nm of shore. As discussed previously, while these rules are specifically directed to enhance spill response in preauthorized zones (generally 3 to 50 m [roughly 5 to 92 km]
|
From page 48... ...
For example, booming and skimming (standard mechanical response techniques) work well in calm conditions and weak currents, whereas dispersants require some minimum wave energy to disperse the surface slick and entrain individual oil droplets.
|
From page 49... ...
. As a consequence, questions about the fate and possible effect of dispersed oil or refined products make up a significant portion of the discussion in Chapters 4 and 5.
|
From page 50... ...
The remaining chapters examine the existing and needed capabilities to understand and predict the impacts of dispersed oil and recommend steps that should be taken to expand capabilities where needed.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.